Method of making dry cells



Dec. 30, 1930.

w. F. HENDRY METHOD OF MAKImf- DRY cmLLS Original Filed July 30, 19 23 2Sheis-Sheet 1 Dec. 30, 1930. w. F. HENDRY METHOD OF MAKING DRY CELLSOriginal Filed July 36, 1 923 2 Sheets-Sheet 2 I 66mm Patented Dec. 30,1930 UNITED STATES PATENT OFFICE WILLIAM FER RISHENDRY, OF OSSINING, NEWYORK, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO NATIONAL CARBON COMPANY,INC., OF NEW YORK, N. Y., A CORPORA- TION OF NEW YORK METHOD OF MAKINGDRY CELL S Original application filed July 30, 1923, Serial No.

application filed June 16,

This invention relates to dry cells and more particularly to a new andimproved method of manufacturing dry cells of uniform efficiency. Thepresent invention is a division of my application Serial No. 654,-

611, filed July 30, 1923, which has matured into] Patent No. 1,637,446,dated August 2,

In accordance with the present invention the depolarizing mixture isintroduced into the dry cell structure in the form of layers, preferablyconsisting of relatively firmly compacted ingredients, and relativelythin layers of conducting material contacting with one of theelectrodes, and projecting towards and terminating near the otherelectrode are provided between the layers of depolarizing mixture.

The layers of depolarizing material are preferably compacted intotablets of any suitable size. In case of a carbon-zinc-manganesedioxiddry cell, these tablets are preferably composed of manganese dioxidmixed I with a relatively small quantity of graphite. This mixture iscompounded under pressure into tablets and, if necessary,a bindingmaterial may be mixed in with it. However, we have found that goodresults are obtained by compressing the mixture while in a dry conditionand without the use of any binder. The tablets may be circular in shapeand provided with a central aperture through which the carbon electrodemay project.

In assembling such a dry cell, the tablets 5 are stacked one on top ofthemther, a thin layer of graphite separating adjacent tablets.Preferably, this thin layer of graphite is obtained by applying a thincoating of finely powdered graphite to each side of a tablet. This maybe readily accomplished by permitting said tablets to slide down a boardto which graphite is being supplied, or in any other suitable manner. Inorder to insure that said layers of graphite be conductively connectedwith the carbon rod, the

654,611. Patent No. 1,637,446. Divided and this 1927. Serial No.199,341.

carbon rod is inserted in the central aperture along with sufficientfinely powdered graphite, preferably by pouring such graphite argund thecarbon rod, While inserting the r0 The method outlined above may bepursued where there is a variation in the diameter of the carbon pencilor of the hole in the annular tablet of depolarizing mixture. Whenhowever, the process of manufacture of these two parts are sufficientlyaccurate, a satisfactory result can .be obtained by merely inserting thecarbon pencil into the hole, the relative sizes insuring a snug fit.

Due to the fact that said layers of graphlte are in close contact withthe carbon electrode, the eflec tive surface of the latter will bematerially increased, these graphite lay- A further advantage of a drycell assembled in accordance with the present invention consists in thatthe tablets of depolarizing mixture may be readily made of uniform sizeand weight, whereby the efficiency of dry cells will be kept more nearlystandard than is possible in a cell in which the depolarizing mixture istamped down. Furthermore, the tablets readily lend themselves to somesuitable automatic making, feeding and assembling processes.

It is possible to secure approximately equal operating advantages bytamping first a layer of depolarizing mix, then a layer of graphite, butsuch a method will not produce a uniform product and does not lend itselto labor saving equipment.

The -invention is illustrated in the en- 5. Thetablets 3 are stacked oneon top of the other and are surrounded with a suitable cellulosecontainer 6. 'By a cellulose container is meant a container of anyporous, textile, paper or fibrous material. The space 7 between thecontainer 6 and the zinc can 1 is filled with flour paste, either byapplying such flour paste to the cellulose container before it isintroduced into the zinc can,'or by pouring such paste into the zinc canafter the cellulose container is in place. The bottom of can 1 may be ofzinc or paper and is separated from the lower end of the carbon rod 2 bymeans of the well known impervious bottom, e. g. of paraifined paper. Asuitable electrolyte must of course be introduced into the dry cell, andit may be sealed in the usual manner by means of an absorbent cushion 10of ground cork or sand and a layer of pitch 11.

Obviously, the invention may be subjected to numerous modificationswithout departing from the spirit thereof. It is applicable to dry cellsof other types than the one herein disclosed, the number, shape andcomposi- I tion of the depolarizing tablets may be varied,

etc. The layers of graphite 4 need not be provided in the form ofcoatings on adjacent tablets 3. The graphite may be formed into tabletslike 3, a binder such as gela-tine being preferably used. In this casetablets 4: and

3 are alternately placed over rod 2 to make up the element. In order toincrease the life of the battery, blotting paper or other absorbentmedium may be introduced, preferably in the form of washers or annulardiscs placed at certain intervals between adjacent tablets, or in anyother suitable manner.

The exciting chemicals may be introduced in a dry form in the mixing ofthe depolarizer or they may be introduced ina liquid form and theresulting mixture dried prior to the molding of the tablets.

One of such modifications is illustrated in Figs. 2, 2a and 2b. In thiscase, the annular tablets 20 are composed mainly of manganese dioxidwith which'a relatively small amount of graphite is mixed. The main bodyof graphite is introduced in the form of an nular tablets 21 of graphitehaving gelatine as a binder. As clearly shown in Fig. 2a, the inside andoutside rims of tablets 21 are turned up, and this tablet is formedpartially to enclose a tablet 20. Tablets 20 and 2.1 are stacked one ontop of the other in any suitizing and able manner, and are introducedwithin a container 22, e. g. of iron and having a llIling 23 of carbon;A zinc electrode 24, the

cross-section of which is shown in Fig. 2b is Instead of the abovementioned ingredients, tablets 20 may be of copper oxide in which casetablets 21 will be thin films or sheets of copper and the carbon lining23 replazed by any other suitable casingor elec; tro e. r

It should be noted also that stacks of tablets 20, 21 may be kept instock suitably wrapped and readyfor assembly with the other elements ofa dry cell. Such stacks will be somewhat in the nature of bobbins, andthe central electrode may be inserted through the apertures beforestorin such bobbins or as a part of a battery assem ly process justprior to the insertion of the bobbin into the container. Beforeinsertion into the container the bobbin is preferably permitted toabsorb the necessary moisture essential to the operation of the battery.

In accordance with a modification of the present invention, thedepolarizer 3 (Fig. 1) may be mixed in a dry condition with a substancesuch as glue or any suitable expansible colloid which will expand whenthe depolarizer absorbs moisture. The cellulose container-6 is in thiscase tightly wrapped around the bobbin and is made of a materialsufiiciently strong to prevent the expansion of tablets 3. Originally,thetablets 3 fit rather loosely around the carbon pencil 2. When,however, the bobbin is soaked and the glue or the like tends to expand,due to the presence of the strong enclosure 6, the tablets 3 will beexpanded inwardly whereby a close fit and therefore good contact will beinsured between the tablets 3 and the carbon rod 2.

What I claim is 1. The method of making dry cells which consists incompacting a mixture of depolarizin and carbonaceous materials intotablets, movmg'the tablets overv a surface supplied with carbonaceousmaterial, passing a carbon electrode centrally through a certain numberof said tablets to form a bobbin, and placing. thebobbin within a zinccontainer electrode.-

2. The method of making dry cells which comprises compacting a mixtureof depolararbonaceous materials into a plurality of t blets; rubbing atleast one side of each of said tablets with graphite to produce anadherent coating thereon which is more conductive than the body of the.tablet, stacking said tablets to provide a bobbin so that at least oneof said coatings lies between each adjacent pair of tablets, and placingsaid bobbin in a zinc container electrode.

3. The method of making dry cells which comprises compacting a mixtureof depolarizing and carbonaceous materials into a plurality of tablets,moving at least one side of each of said tablets in contact withpowdered conductive material so as to produce a conductive layer thereonhaving less resistance to the flow of electric current than the body ofthe tablet, assemblin said tablets to form a bobbin so that the adjacentsides of each adjacent pair of tablets are separated b 1 at least one ofsaid layers, and placing said ohbin in a container electrode. Intestimony whereof, I afiix my signature.

WILLIAM FERRIS HENDRY.

